Means to bias resilient doctor blade



Dec. 19, 1967 H. w. FAEBER MEANS TO BIAS RESILIENT DOCTOR BLADE' Original Filed Jan 8, 1964 INVENTOR. HARRY w. FAEBER his ATTORNEY-5 United States Patent 3,358,643 MEANS T0 BIAS RESILIENT DQCTGR BLADE Harry W. Faeber, Fort Lauderdale, Fla, assignor to Time,

glcorporated, New York, N.Y., a corporation of New ork Continuation of application Ser. No. 336,528, Jan. 8,

1964. This application Aug. 10, 1955, Ser. No. 482,998

3 Claims. (Cl. 118-126) This application is a continuation of the copending application Ser. No. 336,528, filed Jan. 8, 1964, and now abandoned.

This invention relates to a novel blade holder for maintaining a resilient blade in the desired operative relationship with a rotatable cylinder. Although the invention is particularly applicable to web coating machines and will be described herein in that particular application, neverthe less, the invention may also be applicable to other types of machines, such as for use as a doctor blade holder in a printing press.

It has always been recognizedas important in coating machines that the resilient coating blade be properly positioned with respect to the rotating back-up cylinder for the web on which the coating is to be applied by the blade. In many conventional coating machines, the setting and lockup of the coating blade in the blade holder is a tedious and time-consuming task which involves the steps of properly orienting the coating blade in the blade holder and then locking it therein by use of mechanical clamps with the attendant danger that the blade might be displaced in the process, necessitating that the lockup operation be repeated in its entirety. This tedious and time-consuming task was greatly simplified in a blade holder described and claimed in U.S. Letters Patent to Faeber et al., No. 3,057,327, in which blade holder an inflatable tube is substituted for mechanical clamps so that when the blade is properly adjusted in the blade holder it can be inflated to lock up the blade instantly, thereby minimizing the danger that it may become displaced Within the holder during the lockup operation, and another inflatable tube is provided to control the loading of the blade against the backup cylinder.

Another improved blade holder is described and claimed in the patent application of Galer et aL, Ser. No. 119,431, filed June 26, 1961, and now Patent No. 3,273,536, wherein it is recognized that the rigid manner in which coating blades are locked by mechanical clamps does not afford adequate control over the blade and, furthermore, that it may produce irregularities in the blade, such as ripples and other defects, which show up as imperfections in the coating film. To overcome these difiiculties, the improved blade holder described therein afiorded limited freedom of movement to the blade while still maintaining it in proper orientation and alignment with the backup cylinder.

The blade-holding apparatus of the present invention represents a still further significant advance in the art of web coating in that it embodies the combined advantages of the blade holders discussed above, as well as other advantages, in a novel and simplified structure. For example, in the blade holder of the present invention provision is made for quickly and eifeotively locking the coating blade in proper orientation and alignment with respect to the backup cylinder and for pressure-controlled loading of the blade against the backup cylinder without the use of blade distorting clamps which grip the blade between them. This is possible by virtue of the fact that the blade holding apparatus of the present invention utilizes new blade holding principles which provide accurate registration of the blade at the back edge thereof and a stable lockup for the blade by the loading of the coating edge of the blade against the backup cylinder and the engagement "ice of the blade on opposite surfaces by at least two substantially parallel but spaced-apart lines or bands which extend substantially the entire effective length of the coating blade intermediate the coating and back edges of the coating blade.

More specifically, the blade holder of the present invention accommodates the coating blade somewhat loosely in a slot of the blade holder with the coating edge of the blade extending beyond the slot so as to act against the backup cylinder at an acute angle. The slot contains means for registering the back edge of the coating blade so that in the operative position of the blade holder the coating edge of the blade will be properly aligned and oriented with respect to the backup cylinder. The blade holder also embodies means establishing a line or band of contact with the side of the blade which defines an acute angle with the backup cylinder along a line parallel to and spaced apart from the coating edge of the blade, and in addition, means establishing a line or band of contact with the opposite side of the blade along a line parallel to the coating edge but intermediate the coating edge and the first-mentioned line or band of contact. One of the aforesaid blade-engaging means is an extended rigid formation on the blade holder and the other is a resilient, extended pressurecontrolled element carried by the blade holder, and the two extended blade-engaging means, in parallel, offset relationship, cooperate with the backup cylinder to engage and stably hold substantially the entire effective length of the coating blade without exerting a rigid bladeclamping and distorting action on the blade when the proper fluid pressure is brought to bear on the pressurecontrolled element. Thus, in this blade holder the force exerted by the pressure-controlled element not only provides the desired loading of the coating blade against the backup cylinder, but also contributes to the stable lockup of the blade in operative position. The blade holding apparatus of the present invention, therefore, provides a novel and improved device for stably locking up the lade under controlled loading conditions with respect to the backup cylinder without distortion of the blade caused by rigid clamping.

For a complete understanding of the present invention, reference should be made to the detailed description which follows, and to the accompanying drawing in which the figure shows a cross-sectional side view of the blade clamping apparatus of the present invention in operative position with respect to a rotatable backup cylinder.

The blade holding apparatus of the present invention is shown in the drawing as applicable to a web coating machine of the type described in US. Letters Patent to Merrill F. Galer, No. 3,192,895, in which the web to be coated is fed between a rotating backup cylinder and a tank to which coating material is fed and discharged therefrom through a narrow opening defined between the web and a metering bar, and the web is then fed to a coating blade in operative relationship to the backup cylinder so that the coating blade will apply the coating uniformly on the web and remove the excess coating material therefrom. In a web coating machine of this type the coating blade is held in the blade holder in a generally Vertical position. It should be understood, however, that the blade holding apparatus of the present invention is applicable to coating machines of the type described in US. Letters Patent to H. W. Faeber, No. 3,070,066, in which the blade holder maintains the blade in operative position with the backup cylinder at an angle inclined to the horizontal and in which the coating material is fed to the web to be coated by gravity flow across the upper surface of the coating blade.

Referring to the drawing, the blade holding assembly of the present invention, generally designated 10, supports a coating blade A in operative relation to a rotatable backup cylinder B to apply a uniform coating on the surface of a moving web C in contact with the backup cylinder. The blade holding assembly is bolted to a supporting member 11 carried by a pivotal support (partly shown in phantom lines). The pivotal support can be rotated by a fluid controlled actuator (not shown) to carry the blade holder either in a clockwise direction from a retracted position to the operative position shown in the drawing, or in a counterclockwise direction to move the blade holder from the operative to the retracted position.

The blade holding assembly includes a pair of jaws 12 and 13 having opposed, spaced-apart surfaces which define a blade-receiving slot 14 therebetween. The jaw 12 is made in two parts, an upper part 12a mounted by a plurality of screws 15 to a lower part 12b. The lower jaw part 12b is held to the supporting member 11 by threaded bolts 16. The jaw 13, in turn, is afiixed by a series of threaded bolts 17 to the lower jaw part 12b.

The coating blade accommodated within the slot 14 engages a series of pins 18 which bridge the lower end of the slot and serve as a means for registering the bottom or back edge of the coating blade. In the operative position of the coating blade, it is firmly held in its registered position with the coating edge urged against the backup cylinder by the cooperation of parallel and spaced-apart means which engage the blade on opposite surfaces intermediate the registered and coating edgesof the blade along lines or bands extending substantially the entire effective length of the blade. One of the blade-engaging means is preferably a rigid formation, and the other is preferably a pressure-actuated element which urges the blade against the rigid formation and also serves to provide controlled loading of the coating edge of the blade against the backup cylinder.

' In the particular embodiment of the blade holder shown in the drawing, the jaw 13 has integrally formed thereon an extended rigid nose formation 19 which is closely spaced to the opposite surface of the jaw portion 12a to define therebetween a relatively narrow space which is slightly greater than the thickness of the coating blade. The nose formation is spaced apart from and extends parallel to the coating edge of the blade when the latter is registered by the pins 18. The coating blade is urged toward both the nose formation 19 and the backup cylin-V der by an inflatable tube 20, accommodated within a recess 21 of the upper jaw portion 12a, so as to engage the surface of the coating blade opposite the surface engaged by the nose formation along a line or band intermediate the coating edge of the blade and the line or band of engagement between the rigid nose formation and the coating blade. Since the portion of the blade engaged by the inflatable tube is unsupported on the opposite side, at least in that particular region, there is no rigid clamping action on the blade such as might bend to cause distortion thereof. a

The coating blade can be readily dropped into the blade accommodating slot of the blade holder when the blade holder is in retracted position and the tube 20 is in deflated condition. When the blade holder is moved into the operative position shown in the drawing and the tube 20 is inflated at the proper pressure, the blade will be registered with respect to the backup cylinder and the web to be coated in contact therewith, thereby assuring that the blade is properly oriented and aligned with respect to the backup cylinder and the Web. The coating blade will also be firmly locked along three parallel, spaced-apart lines or hands of contact, namely, the line defined by the coating edge of the blade in loaded condition against the backup cylinder, the line or band of contact defined by the rigid nose formation 19 spaced apart by a predetermined distance from the coating edge of the blade, and the line or band of contact exerted by the inflated tube on the opposite surface of the coating blade. The pressure edge of the blade and the web to be coated, thereby producing a non-uniform coating. Such pressure can be minimized by operating a higher fluid pressure within the inflatable tube 20 and by designing the blade holding assembly so that the spacing between the lines or hands of contact by the inflatable tube and the nose formation are less than the spacing between the inflatable tube and the coating edge of the blade. Furthermore, the recess for the tube can be designed so that the tube portion adjacent the blade is flattened somewhat, causing the inflatable tube to act over a somewhat wider band to eliminate variations in the loading of the blade against the backup cylinder resulting from uneven tube expansion.

The invention has been shown and described in a single preferred form and by way of example, and obviously, many modifications and variations can be made therein Without departing from the spirit of the invention. The

invention, therefore, should not be limited to any specified form or embodiment except insofar as such limitations are expressly set forth in the appended claims.

I claim:

1. A blade coating apparatus in which a resilient coating blade of uniform thickness is held in operative position in pressure engagement at an acute angle with the surface to be coated without ripple-producing clamping action on the blade along the region remote from the coating edge comprising a rotatable backup cylinder for guiding the Web to be coated around the lower periphery thereof, a blade holder mounted below the rotatable cylinder for movement toward and away from the rotatable cylinder,

means defining a slot in the blade holder which slot is wider than the thickness of the blade to be accommodated therein, the slot being upright so that the blade can be dropped rear-edge first into the slot and remain therein due to the force of gravity when the blade holder is in inoperative position relative to the rotatable cylinder and the blade is out of pressure engagement with the rotatable cylinder, blade registering means defining the bottom of the slot and registering the coating edge in parallel align ment with the rotatable cylinder, the depth of the slot being such that a substantial portion of the blade projects beyond the slot, the portion of the blade within the slot being unrestrained for uniform, ripple-free deflection to the extent permitted by the width of the-slot and free of ripple-producing influences exerted on the blade, a rigid blade-engaging surface forming the upper end of the slot and adjacent the side of the blade which forms an acute angle with the surface to be coated, said rigid blade-engaging surface engaging a narrow band of the blade at a distance from and extending parallel to the coating edge of the blade, the blade engaging surface and the backup cylinder defining between them a span across which the blade is unsupported on one side, the width of the slot at the rigid blade-engaging surface being Wider than the blad e so that when the blade is in engagement with the said surface the side of the blade directly opposite the said surface is unsupported by engagement with by the blade holder, and a fluid pressure-actuated element carried by the blade holder adjacent the opposite side of the blade intermediate and parallel to both the coating edge of the blade and the rigid blade-engaging surface and directly opposite an unsupported portion of the blade, the movement of the fluid pressure-actuated element against the portion of the blade outside the slot engaging a narrow band of the blade and urging the coating edge of the blade in pressure engagement with the rotatable cylinder and a narrow band more remote from the coating edge against the rigid blade-engaging surface when the blade holder is in operative position relative to the rotatable cylinder, the rotatable cylinder and the rigid blade-engaging surface engaging the blade along two spaced-apart, narrow bands on one side, and the fluid pressure-actuated element engaging the blade along a narrow band intermediate the other two on the other side and cooperating to deflect the blade and hold it firmly without any clamping action whatever on the portion of the blade within the slot.

2. A blade coating apparatus as set forth in claim 1 in which the rigid blade-engaging surface is a continuous nose formation which forms the upper end of the slot and having an upper straightedge spaced from the backup cylinder and defining said unsupported span against which the fluid pressure actuated element acts.

3. A blade coating apparatus comprising a rotatable backup cylinder for guiding the Web to be coated around the periphery thereof, a blade holder, a blade of uniform thickness, means defining a slot in the blade holder which slot is wider than the thickness of the blade to be accommodated therein, blade registering means in the slot and engaging the rear edge of the blade to position the blade in the slot with a substantial portion of the blade projecting beyond the slot, the blade in operative position being at an acute angle with and having its coating edge parallel to the backup cylinder and the web to be coated, blade supporting means forming part of the blade holder and defining a continuous straightedge which extends parallel to the coating edge of the blade and adjacent the side of the blade which forms an acute angle with the backup cylinder, said straightedge being spaced from the coating edge of the blade, and a fluid pressure actuated element carried by the blade holder adjacent the opposite side of the blade and acting against the blade along a band intermediate and parallel with the straightedge and the backup cylinder, the band of the blade on the side opposite the fluid pressure actuated element being unsupported by engagement with the blade holder, so that inflation of the fluid pressure actuated element urges the coating edge of the blade against the web, urges a portion of the blade more remote from the coating edge against the said straight edge, deflects the span of blade extending therebetween and deflects the portion of the blade Within the slot, the backup cylinder, the fluid pressure actuated element, and the means defining the straightedge cooperating to hold the blade firmly in operative position in its registered position against the blade registering means without clamping action on the portion of the blade within the slot while permitting the fluid pressure actuated element to control the loading of the coating blade against the surface to be coated.

References Cited UNITED STATES PATENTS 1,912,605 6/ 1933 Vickery 15256.51 2,579,181 12/1951 Faeber 118261 2,914,788 12/ 1959 Smith et al. 5256.51 3,131,092 4/1964 Coghill 118-413 3,192,895 7/1965 Galer 118-126 MORRIS KAPLAN, Primary Examiner. 

1. A BLADE COATING APPARATUS IN WHICH A RESILIENT COATING BLADE OF UNIFORM THICKNESS IS HELD IN OPERATIVE POSITION IN PRESSURE ENGAGEMENT AT AN ACUTE ANGLE WITH THE SURFACE TO BE COATED WITHOUT RIPPLE-PRODUCING CLAMPING ACTION ON THE BLADE ALONG THE REGION REMOTE FROM THE COATING EDGE COMPRISING A ROTATABLE BACKUP CYLINDER FOR GUIDING THE WEB TO BE COATED AROUND THE LOWER PERIPHERY THEREOF, A BLADE HOLDER MOUNTED BELOW THE ROTATABLE CYLINDER FOR MOVEMENT TOWARD AND AWAY FROM THE ROTATABLE CYLINDER, MEANS DEFINING A SLOT IN THE BLADE TO BE ACCOMMODATED WIDER THAN THE THICKNESS OF THE BLADE TO BE ACCOMMODATED THEREIN, THE SLOT BEING UPRIGHT SO THAT THE BLADE CAN BE DROPPED REAR-EDGE FIRST INTO THE SLOT AND REMAIN THEREIN DUE TO THE FORCE OF GRAVITY WHEN THE BLADE HOLDER IS IN INOPERATIVE POSITION RELATIVE TO THE ROTATABLE CYLINDER AND THE BLADE IS OUT OF PRESSURE ENGAGEMENT WITH THE ROTATABLE CYLINDER, BLADE REGISTERING MEANS DEFININNG THE BOTTOM OF THE SLOT AND REGISTERING THE COATING EDGE IN PARALLEL ALIGNMENT WITH THE ROTATABLE CYLINDER, THE DEPTH OF THE SLOT BEING SUCH THAT A SUBSTANTIAL PORTION OF THE BLADE PROJECTS BEYOND THE SLOT, THE PORTION OF THE BLADE WITHIN THE SLOT BEING UNRESTRAINED FOR UNIFORM, RIPPLE-FREE DEFLECTION TO THE EXTENT PERMITTED BY THE WIDTH OF THE SLOT AND FREE OF RIPPLE-PRODUCING INFLUENCES EXERTED ON THE BLADE, A RIGID BLADE-ENGAGING SURFACE FORMING THE UPPER END OF THE SLOT AND ADJACENT THE SIDE OF THE BLADE WHICH FORMS AN ACUTE ANGLE WITH THE SURFACE TO BE COATED, SAID RIGID BLADE-EN GAGING SURFACE EGAGING A NARROW BAND OF THE COATING EDGE A DISTANCE FROM AND EXTENDING PARALLEL TO THE COATING EDGE OF THE BLADE, THE BLADE ENGAGING SURFACE AND THE BACKUP CYLINDER DEFINING BETWEEN THEM A SPAN ACROSS WHICH THE BLADE IS UNSUPPORTED ON ONE SIDE, THE WIDTH OF THE SLOT AT THE RIGID BLADE-ENGAGING SURFACE BEING WIDER THAN THE BLADE SO THAT WHEN THE BLADE IS IN ENGAGEMENT WITH THE SAID SURFACE THE SIDE OF THE BLADE DIRECTLY OPPOSITE THE SAID 